Trees: Reduce their size safely
Gardeners have to decide if it’s worth reducing the tree’s size if it outgrows its space. While this can usually be done through pruning, it can prove costly and time-consuming. You can also replace the tree by one that fits the space. But this is rarely practical.
It is suitable for…
A tree that has outgrown its garden will need to be cut down. It is better to do it sooner than later. A tree that is too large will take more work to trim and is less likely to recover.
Trees may also need to have their size reduced if they have torn, dead, or diseased branches.
It is usually better to maintain tree and shrub growth under control through regular pruning. This is especially true if you inherit overgrown shrubs and trees in your new garden.
When should trees be cut?
Many trees can be pruned best in the middle of summer, when healing is at its fastest. Prunus (cherry), tree pruning is best done in the middle of summer to lower the risk for silver leaf disease.
Winter pruning is easier for most deciduous trees because the branches are more visible, but it is recommended that you do it before Christmas to avoid bleeding.
How to reduce the tree’s size
There are many options for tree pruning depending on the tree involved and what the desired effect is. They range from the easiest to most difficult.
- All-over trimming in spring or the summer: This technique is only suitable for small formal trees, particularly evergreens. This should be done every other year. These smaller trees can be saved labour by using a long-handled trimmer.
- Pruning a tree that is dormant. This usually involves cutting down the branches all around the tree in order to make it smaller and more attractive. It allows for light to enter the tree, which reduces its vulnerability to wind damage. Also, it is a chance to remove any diseased or damaged wood. For a balanced outcome, take your time and assess the effects of each branch. This is not recommended for silver-leaf trees.
- Pollarding This is a very extreme form to prune. The entire crown or head of the tree is removed. However, it can make the most beautiful small trees.
- Crown lifting Lifting lower branches of the crown will enable you to mow, mulch and enjoy the shade provided by the tree.
- Crown thinning: To let in more sunlight, you can thin out the crowns by removing some (usually up to 30%) of the branches. Then, concentrate on the dead or congested shoots.
A professional arborist should be called in if you need to remove branches that are larger than your wrist or if you have to climb ladders. Professionals are best able to perform crown lifting, pollarding and crown thinning.
Problems
An all-over trimming without taking into account side-branches is a common mistake that can lead to unsightly regrowth and a poor tree shape. These can be removed later to allow the shoots to grow again and give the tree a more attractive shape.
- A lot of material can be removed in one year and this can cause vigorous growth. This can often happen when apples are too meticulously pruned.
- Coral spot could appear on stubs from badly cut branches.
RHS tree experts have stopped recommending pruning or wound painting in most cases. These substances inhibit healing and can encourage rotting. As natural healing occurs most quickly, the ‘collar” (slight swelling at the junction of the trunk and branch) should be kept intact in order to promote healing. You will need to make an angle cut along the trunk. This will allow the collar to remain, but not leave a stub.